public class Main {
    public static void main(String[] args) {
        LinkedList linkedList = new LinkedList();
        linkedList.createList();
        linkedList.addFirst(4);
        linkedList.addFirst(4);
        linkedList.addFirst(4);
        linkedList.addLast(1);

        linkedList.removeAllKey(4);
        linkedList.display();
        System.out.println(linkedList.contains(6));

    }
}
